System, method and apparatus for enhancing wellbore treatment fluid flexibility

ABSTRACT

An apparatus including at least four different modules, the first module being a treatment conditions module structured to interpret a specified pumping rate and a specified salt concentration. The second is a hydration requirements module structured to determine at least one of a hydration vessel fluid volume and a specified temperature in response to the specified pumping rate. The third is a dynamic brine generation module structured to control a flow rate of a first fluid, at least one of a clay stabilizer precursor, an acid precursor and a base precursor; and a polymer material into a hydration vessel in response to the specified salt concentration and the at least one of the hydration vessel fluid volume and the specified temperature. The fourth is a treatment fluid flow module structured to control a flow rate of a treatment fluid from the hydration vessel in response to the specified pumping rate.

This application claims priority as a divisional application of U.S.patent application Ser. No. 12/511,182, filed Jul. 29, 2009. Thedisclosure of the priority application is incorporated by referenceherein in its entirety.

BACKGROUND

The technical field generally relates to treatment fluids for productionor injection wells, and more particularly but not exclusively relates totreatment fluids including a hydrated polymer. Treatment fluidsincluding a polymer generally require hydration of the polymer todevelop the desired viscosity for the treatment. Typically, the polymerbased treatment fluid is created in a batch in advance of commencing thetreatment. Many wells intersect formations that are sensitive to freshwater and the treatment fluids for such wells include a clay stabilizersuch as a potassium chloride or other brine. The brines utilized for thetreatment fluids are also often created in a batch in advance ofcommencing the treatment. Presently available systems for generatingtreatment fluids result in a long overall treatment cycle from the timeof fluid creation to the time of the completion of the treatment.Additionally, presently available systems are relatively inflexible totreatment fluid design changes in real time, which can result ininsufficient treatment fluid available during a treatment or in anexcessive treatment fluid remainder, and have a relatively inflexibletreatment fluid temperature. Excessive remaining treatment fluidintroduces increase cost, resource consumption, and imposes disposalcosts and risks. Therefore, further technological developments aredesirable in this area.

SUMMARY

One embodiment is a unique method for rapidly hydrating a wellboretreatment fluid. Other embodiments include unique systems and apparatusto rapidly adjust wellbore treatment parameters. Further embodiments,forms, objects, features, advantages, aspects, and benefits shall becomeapparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a system for enhancing wellboretreatment fluid flexibility.

FIG. 2 is a schematic diagram of a processing subsystem that executescertain operations for enhancing wellbore treatment fluid flexibility.

FIG. 3 is an illustration of a hydration time versus hydrationtemperature for a fluid.

FIG. 4 is an illustration of a hydration progress verses time for afluid.

FIG. 5 is an illustration of performing a chemical process andtransferring heat from the chemical process to a first fluid.

FIG. 6 is an illustration of performing a chemical process by adding thefirst chemical reactant to a first fluid and further adding a secondchemical reactant to the first fluid.

FIG. 7 is a schematic flow diagram of a process for enhancing wellboretreatment fluid flexibility.

FIG. 8 is a schematic flow diagram of an alternate process for enhancingwellbore treatment fluid flexibility.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, any alterations and further modificationsin the illustrated embodiments, and any further applications of theprinciples of the invention as illustrated therein as would normallyoccur to one skilled in the art to which the invention relates arecontemplated herein.

FIG. 1 is a schematic diagram of a system 100 for enhancing wellboretreatment fluid flexibility. The system 100 includes a fluid source 102that provides a first fluid 104, a base source 105 that provides a basematerial 106, and an acid source 108 that provides an acid material 110.The base material 106 may be an anhydrous base, a base precursor, and/ora concentrated base. Non-limiting examples of base materials 106 includebase material includes sodium hydroxide, potassium hydroxide, ammonia,tetramethyl ammonium hydroxide, and/or cesium hydroxide. The basematerials 106 may be clay stabilizer precursors, and other non-limitingexamples of base materials 106 include sodium, potassium, magnesium,sodium hydride, lithium hydride, calcium hydride, magnesium hydride, ametal, a metal hydride, and/or a metal oxide. The acid material 110 maybe an anhydrous acid, an acid precursor, and/or a concentrated acid.Non-limiting examples of acid materials 110 include HCl(g), HCl(aq),HBr(g), HBr(aq), HI(g), HI(aq), and/or formic acid. In certainembodiments, the base materials 106 and/or acid materials 110 arepresent in more than one form or concentration, allowing, for example,temperature control of the first fluid 104 entering a hydration vessel116 by varying the temperature generated (e.g. by heat of mixing and/orheat of dissolution) in the first fluid 104.

The system 100 further includes a polymer source 112 that provides apolymer material 114. The polymer material includes any polymer known inthe art, such as xanthan, hydroxy-ethyl-cellulose, guar,carboxy-methyl-hydroxy-propyl-guar, a poly-saccharide, a poly-saccharidederivative, a poly-acrylamide, a poly-acrylamide co-polymer, diutan,hydroxyl-propyl guar, and/or a synthetic polymer. The polymer material114 may be added in any form known in the art, including at least apowder and a hydrocarbon-based slurry (e.g. slurried in oil, organicsolvent, or diesel).

The presence of, and order of, each of the sources 105, 108, 112 isoptional. For example, the acid source 108 may occur before the basesource 105, and/or the first fluid 104 may include any of the acid,base, and/or polymer materials 106, 110, 114 with the remainingmaterials 106, 110, 114 added to the first fluid 104 such that heat isgenerated, a dynamic polymer level is achieved, and/or a dynamic claystabilizer concentration is achieved.

The system 100 further includes a hydration vessel 116 fluidly coupledto the fluid source 102, the base source 105, the acid source 108, andthe polymer source 112. The system 100 further includes a fluid conduit118 fluidly coupled to the material sources 105, 108, 112 on an upstreamside and fluidly coupled to a treatment pump 144 on a downstream side.The fluid conduit 118 further continues to the wellhead 148. Thehydration vessel 116 is illustrated as a continuous stirred tank reactor(CSTR) having a volume and an amount of treatment fluid 120 therein.However, the hydration vessel 116 may be any type of vessel includingthe fluid conduit 118, from any portion downstream of where all of thematerials 106, 110, 114 are added, up to and including a portion of thewellbore 150 volume. For example, where the fluid pumping rate of thepump(s) 144 is 30 barrels per minute (bpm) and the hydration vessel 116comprises 45 barrels of total volume of fluid conduit 118 plus wellbore150 volume above a formation of interest 152, there is a potentialresidence time of 90 seconds available for the treatment fluid 120 afterthe mixing of the materials 106, 110, 114. In another example, where thefluid pumping rate of the pump(s) 144 is 30 bpm and the hydration vesselcomprises a 60 barrel capacity CSTR, there is a potential residence timeof 120 seconds available for the treatment fluid 120 after the mixing ofthe materials 106, 110, 114, if the downstream fluid conduit 118 andwellbore 150 volumes are ignored.

One of skill in the art will understand the tradeoffs between using atank as a hydration vessel 116 and utilizing the fluid conduit 118and/or wellbore 150 volume as the hydration vessel 116. Generally, andwithout limitation, the use of a tank or CSTR allows for more precisecontrol of the composition, temperature, and polymer hydration level ofthe treatment fluid 120, provides for a uniform treatment fluid 120exiting the hydration vessel 116, and provides for smooth transitions incomposition, temperature, and polymer hydration level. Utilization ofthe fluid conduit 118 and/or wellbore 150 volume allows for moreresponsive changes to the composition, temperature, and polymerhydration level of the treatment fluid 120 as well as providing for lessequipment and a more limited footprint on the location of the system100. In certain embodiments, the hydration vessel 116 comprises thevolume of the tank, the fluid conduit 118, and/or the wellbore 150volume.

The system 100 further includes a controller 122. The controller 122 isa portion or all of a processing subsystem that executes certainoperations for enhancing treatment fluid flexibility. The controller 122may include a computer program product on a computer readable mediumthat performs operations for enhancing treatment fluid flexibility. Thecontroller 122 may include aspects in hardware and/or software, mayinclude portions on a computer, portions hardwired, and/or portionsexecuted by an operator (not shown), and the controller 122 may be asingle device or a two or more distributed devices that operatesimultaneously and/or inter-communicate via datalinks, networks,electronic signals, and/or wireless communications.

The exemplary controller 122 is in communication with one or more fluidstreams—for example via density sensors 138 and/or temperature sensors139. The controller may further be in communication with one or moredevices such as the hydration vessel 116, a fluid delivery pump 132,and/or a heat exchanger pump 146. The controller may be in communicationwith any sensor, device, or actuator in the system 100, and the sensors138, 139 may not all be present, and additional sensors not shown may bepresent. The selection of sensors to support functions of the controller122 is a mechanical step for one of skill in the art and is notdiscussed in detail herein except where such detail may enhance clarity.

The exemplary system 100 further includes a bypass line 154 (flowingthrough bypass valve 140) fluidly coupling a diluted fluid (e.g. thefirst fluid 104) to the treatment fluid 120 downstream of the hydrationvessel 116. The bypass line 154 is illustrated as joining the fluidconduit 118 just before a blender 142. In certain embodiments, where thehydration vessel 116 includes portions of the fluid conduit 118 or evenportions of the wellbore 150 volume, the bypass line 154 may join at alater point. Examples of joining points include, without limitation,points downstream of the blender 142, downstream of the pump 144, and/orwithin the wellbore 150. In one example, the diluted fluid is pumpeddown one of a tubing or an annulus, the treatment fluid 120 is pumpeddown the other, and the fluids are joined within the wellbore 150. Thereare no limitations as to how many joinder points the bypass line 154 mayhave with the main treatment line, or where the fluids may be joined.However, the inclusion of the diluted fluid with the treatment fluid 120will generally bring the temperature of the treatment fluid 120 backdown and slow hydration, so the joinder point is a design criteria basedon the amount of time the treatment fluid 120 is supposed to maintain anelevated temperature.

In certain embodiments, the system 100 further includes one or more heatexchangers 136, 134 thermally coupled to the fluid conduit 118. The heatexchangers 136, 134 provide the controller 122 with actuators to controla temperature of the treatment fluid 120 at the wellhead 148. In oneexample, the controller 122 controls the heat exchanger(s) 136, 134 suchthat a temperature of the treatment fluid 120 exiting the fluid conduit118 at the wellhead 148 is not more than 10° C. warmer than atemperature of the first fluid 104. A first heat exchanger 134 transfersheat to the ambient environment, and the heat exchanger pump 146controls a rate of heat transfer through the heat exchanger 134 byvarying an amount of ambient air through the first heat exchanger 134.

A second heat exchanger 136 transfers heat from the treatment fluid 120at a position where it is no longer needed to the first fluid 104entering the hydration vessel 116. The heat transferred in the heatexchanger 136 is heat provided from the chemical process that heatedfluid in the hydration vessel 116. The heat exchanger 136 can becontrolled by varying exchange area, by a partial or complete bypass oneither the first fluid 104 or treatment fluid side 120 (not shown) or byother mechanisms known in the art. The heat exchangers 134, 136 areexemplary only and may be of any type.

The controller 122 controls a flow rate of a treatment fluid 120 fromthe hydration vessel 116 in response to a specified pumping rate. Thecontroller 122 further controls a flow rate of the first fluid 104, thebase material 106, the acid material 110, and the polymer material 114into the hydration vessel 116 such that the treatment fluid 120 residingin the hydration vessel includes a specified salt concentration, andsuch that an average residence time of the treatment fluid 120 in thehydration vessel 116 is at least equal to a hydration time. Thehydration time may be a time for the fluid to achieve a specifiedpercentage of full hydration at the temperature within the hydrationvessel 116.

For example, referencing FIG. 3, an illustration 300 shows a first curve302 showing a time to 80% hydration and a second curve 304 showing atime to 90% hydration. It is seen in the illustration that the hydrationtime decreases dramatically with elevated temperature. The data in theillustration 300 is exemplary for one set of conditions only, butsimilar data is easily obtained as a matter of standard rheologicaltesting by one of skill in the art. Data such as that in theillustration 300 can be utilized to determine a match of hydrationvessel 116 volume, hydration time, and treatment fluid temperature 220to achieve the desired hydration. Typically, the fluid pumping rate ofthe treatment is a value fixed for other reasons and is not a designcriterion for sufficient hydration of the treatment fluid 120.Therefore, in certain embodiments, one of the treatment fluidtemperature or the hydration vessel 116 volume is fixed, and theappropriate hydration curve 302, 304 (or other curve where 80% or 90%are not the desired hydration criteria) determines the hydration time.In real time during a treatment, the controller 122 can modulate thehydration vessel 116 volume (e.g. by maintaining a higher or lower fluidlevel in the hydration vessel 116) and the treatment fluid 120temperature to ensure the treatment fluid 120 achieves the designedhydration amount. The controller 122 controls the treatment fluid 120temperature by any one or more of the following behaviors: utilizing amore concentrated acid material 110 and/or base material 106, utilizinga lower percentage of treatment fluid 120 and a greater percentage offluid from the bypass line 154, modulating a heat exchange amount in thefirst heat exchanger 134, and/or modulating a heat exchange amount inthe second heat exchanger 136.

Referencing FIG. 4, a first curve 402 illustrates a polymer hydrationpercentage at an ambient temperature, and a second curve 404 illustratesthe polymer hydration percentage at an elevated temperature (66° C. inthe example). The data in the illustration 400 is exemplary for one setof conditions only, but similar data is easily obtained as a matter ofstandard rheological testing by one of skill in the art. Data such asthat in the illustration 400 can be utilized by the controller 122 toensure that sufficient hydration is achieved during the treatment. Infurther example to those above, the controller 122 may have a storedrange of hydration percentages acceptable during transition periods andthe like, and may utilize data such as that in the illustration 400 tomanage transitions. In a non-limiting example, a treatment pumping ratechange occurs that the controller 122 determines will result in atreatment fluid 120 temperature increase for sufficient hydration tooccur. The controller 122 may determine that a move to 70% istemporarily acceptable, according to pre-determined criteria, during thetransition as the treatment fluid 120 temperature is raised. Thecontroller 122 may interpolate between available data, and/or theincluded data may have additional curves beyond those illustrated. Anexemplary controller 122 is explained in greater detail in relation tothe description referencing FIG. 2.

The data illustrated in FIGS. 3 and 4 is not needed for certainembodiments of the system 100. The controller 122 can control to fixeddesign points determined ahead of time, and/or can respond to changes inpumping rates, brine concentrations and/or polymer loading amountsaccording to pre-defined criteria. However, data such as thatillustrated in FIGS. 3 and 4, when available to the controller 122, canprovide for more flexible response from the controller 122.

For embodiments where fluid is flowing in the hydration vessel 116, thedeterminations (e.g. the temperature, salt concentration, or thehydration percentage) for the fluid residing in the hydration vessel 116are considered at a design point where the fluid is expected to have thespecified salt concentration and be sufficiently hydrated. For example,if the specified pumping rate is 30 bpm, and a flow through a bypassvalve 140 is 24 bpm, the controller 122 controls the flow rates of thefirst fluid 104, the base material 106, the acid material 110, and thepolymer material 114 such that the fluid leaving the hydration vessel116 combined with the fluid through the bypass valve 140 is a total of30 bpm at the specified salt concentration. If the hydration vessel 116is further considered to include a first 1,000 feet of the wellbore 150,the controller 122 further controls a temperature of the treatment fluid120 such that sufficient hydration is achieved by 1,000 feet into thewellbore 150.

While the system 100 is illustrated mixing an acid material 110 and abase material 106 into a first fluid 104, the system 100 can include anychemical process that generates heat and thereby accelerates hydrationof the polymer material 114. For example, a polymerization reaction canoccur, where the product of the polymerization reaction and the heat ofthe polymerization reaction are included in the treatment fluid 120. Anon-limiting example of a polymerization that can be used includes theaddition of one or more of the monomers selected from acrylates,methacrylates, acrylic acid, and methacrylic acid. In one example,acrylic acid is polymerized into polyacrylic acid, and the heat andreaction product from the polymerization are included in the treatmentfluid 120. In another example, a condensation polymerization isperformed (e.g. using phenol formaldehyde) and the resulting heat andproduct are included in the treatment fluid 120.

The heat of the chemical process and the product of the chemical processcan be added to the treatment fluid 120 at separate times, for examplethe heat may be added first, or they may be added simultaneously. Inadditional or alternative embodiments, the system 100 can include aprocess that allows the brine concentration in the treatment fluid 120to be altered in real-time, and/or a process that allows a concentrationof the polymer material 114 in the treatment fluid to be altered inreal-time. Further, the system 100 can include a process that allows atemperature of the treatment fluid 120 at the wellhead 148 to be alteredin real-time. The implementations of these features are understood toone of skill in the art having the benefit of the disclosures herein.

The system 100 is illustrated at a standard land location. However, thelocation may be any type of location known in the art. For example, andwithout limitation, the location may be contained on a rig (e.g. in anenvironmentally sensitive area), on a skid, on a truck, on a ship,and/or on a sea based platform. In certain embodiments, the system 100is especially useful where disposal of treatment fluid 120 is expensiveor unacceptable, and/or where physical space is limited.

FIG. 2 is a schematic diagram of a processing subsystem 200 including acontroller 122 that executes certain operations for enhancing wellboretreatment fluid flexibility. The exemplary controller 122 includesmodules structured to functionally execute operations for enhancingtreatment fluid flexibility. The description herein includes the use ofmodules to highlight the functional independence of the features of theelements described.

A module may be implemented as operations by software, hardware, or atleast partially performed by a user or operator. In certain embodiments,modules represent software elements as a computer program encoded on acomputer readable medium, wherein a computer performs the describedoperations when executing the computer program. A module may be a singledevice, distributed across devices, and/or a module may be grouped inwhole or part with other modules or devices. The operations of anymodule may be performed wholly or partially in hardware, software, or byother modules. The presented organization of the modules is exemplaryonly, and other organizations that perform equivalent functions arecontemplated herein. Modules may be implemented in hardware and/orsoftware on computer readable medium, and modules may be distributedacross various hardware or software components.

The controller 122 includes a treatment conditions module 202 thatinterprets a specified pumping rate 212 and a specified saltconcentration 216. Interpreting includes any determination of theparameters by any means, including at least receiving a signal from asensor, receiving a user input, reading a value from a computer memorylocation, receiving a value from a network or datalink communication,receiving a value from an electronic signal, and/or calculating a valuebased upon other available parameters. The controller 122 furtherincludes a hydration requirements module 204 that determines a hydrationvessel fluid volume 232 and/or a specified temperature 210 in responseto the specified pumping rate 212. The specified temperature 210 appearstwice, because the specified temperature 210 may be an input received atthe treatment conditions module 202 and/or an output of the hydrationrequirements module 204. Where the specified temperature 210 is a designconstraint, it will appear as an input, but may be further modified bythe hydration requirements module 204.

The controller 122 further includes a dynamic brine generation module206 that controls a first fluid flow rate 234, a base material flow rate236, an acid material flow rate 238, and/or a polymer material flow rate240 in response to the specified salt concentration 216 and further inresponse to the hydration vessel fluid volume 232 and/or the specifiedtemperature 210. The controller 122 further includes a treatment fluidflow module 208 that controls a treatment fluid flow rate 242 inresponse to the specified pumping rate 212. The dynamic brine generationmodule 206 and the treatment fluid flow module 208 may utilize anycontrol scheme known in the art—for example the treatment fluid flowmodule 208 may control a valve and/or pump out of the hydration vesselto achieve the treatment fluid flow rate 242, or the portion of thetreatment fluid flow rate 242 that is not attributable to the dilutedfluid. The dynamic brine generation module 206 may utilize a PIDcontroller or other scheme to maintain a fluid level, brineconcentration, and/or present temperature of the treatment fluid 220 inthe hydration vessel.

The dynamic brine generation module 206, in certain embodiments,includes control elements tailored to the system 100 that reflect thedesign priorities of the system 100. For example, the dynamic brinegeneration module 206 may include feedforward models of heats ofdissolution, heats of mixing, and/or heats of reaction to determine thetemperature effects of the various streams entering the hydrationvessel, and further may include a schedule of parameter priorities tomanage transitions as real-time treatment requirements impose changes onthe system. For example, and without limitation, the dynamic brinegeneration module 206 may draw down (or allow an increase in) thehydration vessel volume preferentially to allowing the brineconcentration or treatment fluid temperature 220 to vary, and mayincrease or decrease the treatment fluid to dilute fluid ratio tomaintain the fluid compositions preferentially to changing the hydrationvessel volume. Further, the dynamic brine generation module 206 mayevaluate cost factors, such as allowing minor variations in thetreatment fluid temperature 220 preferentially to invoking a highconcentration base material that may allow greater heat generation butmay be expensive. The provided control behaviors are exemplary only, andalternate or additional behaviors known in the art may be included. Theselection of control schemes, prioritization, and cost optimization forthe operations of the dynamic brine generation module 206 and thetreatment fluid module 208 are understood to those of skill in the artwith knowledge generally available regarding a target system 100combined with the benefit of the disclosures herein.

In an exemplary embodiment, the treatment conditions module 202interprets the specified temperature 210, and the hydration requirementsmodule 204 determines the hydration vessel fluid volume 232 in responseto the specified pumping rate 212. In another exemplary embodiment, thetreatment conditions module 202 interprets the hydration vessel fluidvolume 232, and the hydration requirements module 204 determines thespecified temperature 210 in response to the specified pumping rate 212.In certain embodiments, the hydration requirements module 204 determinesa hydration time 230 in response to the specified temperature 210 and/ora present temperature of the treatment fluid 220 in the hydrationvessel. The hydration time 230 may be utilized by the dynamic brinegeneration module 206 and/or the treatment fluid module 208 as afeedforward or feedback parameter, for example to adjust the flow rates234, 236, 238, 240, to increase or decrease the treatment fluidtemperature 220, to adjust the treatment fluid flow rate 242, and/or toallow the volume of fluid in the hydration vessel to change.

The specified temperature 210 may be a temperature determined to enhancea hydration time of the gel or polymer material into the treatmentfluid. In certain embodiments, the specified temperature is atemperature at least 50° C. warmer than a temperature of the first fluid226, a temperature of at least 65° C., and/or a temperature determinedin response to an available volume of the hydration vessel and thespecified pumping rate. The specified temperature 210 may be obtainedfrom data such as that depicted in the illustrations 300, 400 of FIGS. 3and 4.

In an exemplary embodiment, the treatment conditions module 202interprets a dynamically updated specified temperature 228, and thecontroller 122 responds to the dynamically updated temperature 228. Incertain embodiments, the dynamic brine generation module 206 controlsthe flow rates 234, 236, 238, 240 in response to the dynamically updatedspecified temperature 228. In alternate or additional embodiments, thecontroller 122 modulates a heat exchange amount in the first heatexchanger 134 and/or the second heat exchanger 136 in response to thedynamically updated specified temperature 228. The ability to utilize adynamically updated specified temperature 228 allows, withoutlimitation, modulation of the hydration time 230 or response to changingdownhole temperature during the treatment.

In an exemplary embodiment, the treatment conditions module 202interprets a dynamically updated salt concentration 218, and the dynamicbrine generation module 206 controls the flow rates 234, 236, 238, 240in response to the dynamically updated salt concentration. The abilityto dynamically adjust the salt concentration (and/or a clay stabilizerconcentration) allows for improved well productivity and/or injectivity,and/or allows for a reduced chemical consumption and job cost, as wellas reducing the chemical burden in any flowback fluid that may requiretreatment or disposal. For example, a salt concentration may beincreased in portions of the treatment fluid that are expected to havesignificant exposure to the formation of interest. In the example, asalt concentration in the pad stage of a hydraulic fracturing treatmentmay be increased because a significant portion of that fluid is expectedto contact or leak off into the formation, where the final stage of thefracture treatment may include a lower salt concentration. The describedoperations for utilizing a dynamically updated salt concentration 218are exemplary and non-limiting.

During nominal operation, the treatment conditions module 202 determinesa specified gel loading concentration 222 and the dynamic brinegeneration module 206 controls the flow rates 234, 236, 238, 240 suchthat the treatment fluid includes the specified gel loadingconcentration 222. In an exemplary embodiment, the treatment conditionsmodule 202 interprets a dynamically updated gel loading concentration224, and the dynamic brine generation module 206 controls the flow rate240 of the polymer material into the hydration vessel further inresponse to the dynamically updated gel loading concentration 224.

The ability to dynamically adjust the gel loading allows for improvedwell productivity and/or injectivity, allows for a reduced chemicalconsumption and job cost, reduces the chemical burden in any flowbackfluid that may require treatment or disposal, and allows for otheradjustments to the treatment that are otherwise difficult or notpossible. For example, reductions of gel loading in certain stages allowa reduced amount of crosslinker, breaker, or other additives in additionto less gel and damage being introduced into the formation of interest.The ability to change the gel loading also results in, for example, theability to dynamically adjust the proppant schedule (e.g. going to ahigher proppant concentration than a base gel loading would support),the ability to dynamically adjust a fluid viscosity, the ability tointroduce slugs of very high gel loading for fluid diversion, and theability to rapidly reduce the gel loading during an imminent screenoutduring a treatment. The described operations for utilizing a dynamicallyupdated gel loading concentration 224 are exemplary and non-limiting.

FIG. 5 is an illustration 500 of performing a chemical process andtransferring heat from the chemical process to a first fluid. In theillustration 500, a first stream 502 is added to a second stream 504 atmixing location 506, and a resultant stream 508 includes a chemicalproduct and an amount of heat from the chemical process. In one example,the first stream 502 is about 300 kg/min of water at a temperature ofabout 25° C., the second stream 504 is about 60 kg/min of anhydrouspotassium hydroxide at about 25° C., and the resultant stream 508 is a16.6% KOH(aq) solution at about 66° C. if heat losses to the environmentare ignored. The resulting stream receives about 57,600 kJ/kg of the KOHdissolved into the water. The determinations of the exemplary streams,including the heat generated from dissolution, mixing, or reaction ofthe components, the enthalpies and heat capacities of all streams, andthe resulting products and temperatures are mechanical steps for one ofskill in the art. The determinations illustrated are examples similar toa feedforward model that may be utilized in a controller 122 to achievethe specified temperature 210.

FIG. 6 is an illustration of performing a chemical process andtransferring heat from the chemical process to a first fluid. In theillustration 600, a first stream 602 is added to a second stream 604 ata first mixing location 606 and a first resultant stream 608 includes afirst chemical product and a first amount of heat from the chemicalprocess. A third stream 610 is added to a fourth stream 612 at a secondmixing location 614 and a second resultant stream 616 includes a secondchemical product and a second amount of heat from the chemical process.The first resultant stream 608 is added to the second resultant stream616 at a third mixing location 618 and a third resultant stream 620includes a third chemical product and a third amount of heat from thechemical process. The streams are added at various mixing locations 606,614, 618 to isolate the heat contributions of the various chemicalprocesses, but differing configurations of mixing locations, includingadding of all streams directly into a hydration vessel, are contemplatedherein.

In the example, the first resultant stream 608 is assumed to be similarto the resultant stream 508 referenced in relation to FIG. 5. The thirdstream 610 is anhydrous HCl(g) at about 39 kg/min and about 25° C.,while the fourth stream 612 is about 400 kg/min of water at about 25° C.The addition of anhydrous HCl to water is known to generate about 74,840kJ/kg HCl, so the a second resultant stream 616 is formed having 8.9%HCl(aq) at about 69° C. Further in the example, the addition of thefirst resultant stream 608 to the second resultant stream 616 releasesabout 55.20 kJ/kg KOH that is neutralized, resulting in the thirdresultant stream 620 which is a 10% KCl solution at about 85° C.

In the example, the hydration time to 90% for many polymers would beunder about 100 seconds, so the hydration vessel volume where 90%hydration is the target would be sized around 1.67 times the bpm ratefor the treatment. In the example, if the designed KCl concentrationdownstream of the hydration vessel was 2%, about 4 parts dilution fluidper part of treatment fluid in the hydration vessel would be added,resulting in a 2% KCl solution. In the example, if the dilution fluid isat a temperature of about 25° C., the resulting fluid after dilutionwould be about 37° C., neglecting heat losses. If it is desired that thefinal treating fluid be cooler, for example within about 10° C. of thefirst fluid and/or dilution fluid, various methods can reduce the finaltemperature, including at least a heat exchanger, utilization ofconcentrated acid and/or base rather than an anhydrous acid or base,utilization of an endothermic reaction in the chemical process, and/oran enhancement of the heat transfer from the system 100 to the ambientenvironment.

The schematic flow diagrams in FIGS. 7 and 8, and the relateddescriptions which follow, provide illustrative embodiments ofperforming procedures for enhancing the wellbore treatment fluidflexibility. Operations illustrated are understood to be exemplary only,and operations may be combined or divided, and added or removed, as wellas re-ordered in whole or part, unless stated explicitly to the contraryherein.

FIG. 7 is a schematic flow diagram of a procedure 700 for enhancingwellbore treatment fluid flexibility. The procedure 700 includes anoperation 702 to perform a chemical process to create a chemical productand an amount of heat, and an operation 704 to transfer at least aportion of the amount of heat to a first fluid. Examples of the amountof heat transferred to the first fluid include enough to heat the firstfluid at least 50° C., enough to heat the first fluid to at least 65°C., and/or enough to heat the first fluid to a temperature wherein apolymer hydration can occur within an available hydration vessel volumeat a specified pumping rate. The procedure 700 further includes anoperation 706 to hydrate an amount of polymer in the first fluid, and anoperation 708 to combine the chemical product with the first fluid togenerate a treatment fluid. The exemplary procedure 700 further includesan operation 709 to dilute the treatment fluid with respect to at leastone constituent. Non-limiting examples of the operation 709 includeadding water to the treatment fluid to dilute a brine concentration anda gel concentration, adding a fresh water gel to the treatment fluid todilute the brine concentration, and adding a brine to the treatmentfluid to dilute the gel concentration.

The exemplary procedure 700 further includes an operation 710 to providea heat transfer environment such that a temperature of the treatmentfluid at a wellhead is ≦10° C. greater than a temperature of the firstfluid. The procedure 700 includes an operation 712 to treat a formationof interest with the treatment fluid, where the formation of interestintersects a wellbore.

Non-limiting examples of chemical processes performed in the operation702 to perform the chemical process include a solid dissolution, a gasdissolution, a liquid dissolution, a liquid dilution, and/or a chemicalreaction. Alternate or additional chemical processes include mixing anacid with a base, where the chemical product is a salt such as sodiumchloride, potassium chloride, ammonium chloride, tetramethyl ammoniumchloride, calcium chloride, magnesium chloride, sodium bromide, calciumbromide, zinc bromide, potassium formate, cesium formate, and/or zincchloride. Even further alternate or additional chemical processesinclude mixing an anhydrous base with water or a diluted base, dilutinga concentrated base, mixing an anhydrous acid with water or a dilutedacid, and/or diluting a concentrated acid. Still further alternate oradditional chemical processes include inducing a polymerization reactionwhere the chemical product is a treatment fluid additive, and/orperforming the chemical process by adding a salt to water or a dilutebrine.

FIG. 8 is a schematic flow diagram of an alternate procedure 800 forenhancing wellbore treatment fluid flexibility. The procedure 800includes an operation 802 to provide a first fluid and an operation 804to provide a first and second chemical reactant. The first and secondchemical reactants each include a reactant from the reactants includingdilute acid, dilute base, concentrated acid, concentrated base,anhydrous acid, anhydrous base, a metal, a metal hydride, a metal oxide,and/or a monomer for a polymerization reaction. The procedure 800further includes an operation 806 to perform a chemical processincluding the first and second chemical reactants, and an operation 808to transfer an amount of heat from the chemical process to the firstfluid. In certain embodiments, the operation 806 may include only one ofthe first and second chemical reactants. The operation 806 includesadding the first and second chemical reactants in any order, for exampleadding the second chemical reactant to the first fluid before the firstchemical reactant, or adding the first and second chemical reactantssimultaneously. The procedure 800 further includes an operation 810 tohydrate a polymer in the first fluid, and an operation 812 to treat aformation of interest with a treatment fluid including the heated firstfluid and a chemical (or reaction) product of the chemical process. Theprocedure 800 may further include (not shown) an operation to dilute thetreatment fluid with respect to at least one constituent of thetreatment fluid.

The exemplary procedure 800 further includes an operation 814 todetermine whether a treatment should be shortened. In response to theoperation 814 indicating the treatment should be shortened, theprocedure 800 includes an operation 816 to stop the treatment before apre-determined amount of treatment fluid is injected into the well, andan operation 818 to consume less than a design amount of the firstchemical reactant. The operation 818 to consume less than a designamount of the first chemical reactant includes having a usable amount ofthe first chemical reactant leftover that is readily available for usein a future treatment.

In response to the operation 814 indicating the treatment should not beshortened, the procedure 800 includes an operation 820 to determinewhether to extend the treatment. In response to the operation 820indicating the treatment should be extended, the procedure 800 includesan operation 822 to continue the treatment after a pre-determine amountof treatment fluid is injected. In certain embodiments, the operation822 to extend the treatment includes extending the treatment such thatat least 60 m³ greater than the pre-determined amount of the treatmentfluid is injected into the formation of interest.

As is evident from the figures and text presented above, a variety ofembodiments according to the present invention are contemplated.

One exemplary embodiment is a method including performing a chemicalprocess to create a chemical product and an amount of heat, transferringat least a portion of the amount of heat to a first fluid, and hydratingan amount of polymer in the first fluid. The method further includescombining the chemical product with the first fluid to generate atreatment fluid, and treating a formation of interest with the treatmentfluid. The formation of interest intersects a wellbore. The method mayfurther include diluting the treatment fluid with respect to at leastone constituent of the treatment fluid, for example reducing a brineand/or gel concentration in the treatment fluid. The exemplary methodfurther includes performing the chemical process as one of a soliddissolution, a gas dissolution, a liquid dissolution, a liquid dilution,and/or a chemical reaction. The method may include performing thechemical process by mixing an acid with a base, and the chemical productis a salt such as sodium chloride, potassium chloride, ammoniumchloride, tetramethyl ammonium chloride, calcium chloride, magnesiumchloride, sodium bromide, calcium bromide, zinc bromide, potassiumformate, cesium formate, and/or zinc chloride. The method includesperforming the chemical process by a process selected from: mixing ananhydrous base with water or a diluted base, diluting a concentratedbase, mixing an anhydrous acid with water or a diluted acid, and/ordiluting a concentrated acid.

In certain embodiments, the method includes performing the chemicalprocess which includes adding a base material to water or a dilutedbase, where the base material is an anhydrous base and/or a concentratedbase, and where the base material includes sodium hydroxide, potassiumhydroxide, ammonia, tetramethyl ammonium hydroxide, and/or cesiumhydroxide. In certain embodiments, the method includes performing thechemical process by adding an acid material to water or a diluted acid,where the acid material is an anhydrous acid and/or a concentrated acid,and where the acid material includes HCl(g), HCl(aq), HBr(g), HBr(aq),HI(g), HI(aq), and/or formic acid. Certain embodiments of the exemplarymethod include performing the chemical process which comprises adding aclay stabilizer precursor to water, where the clay stabilizer precursoris sodium, potassium, magnesium, sodium hydride, lithium hydride,calcium hydride, magnesium hydride, a metal, a metal hydride, and/or ametal oxide. Certain embodiments of the exemplary method includeperforming the chemical process by inducing a polymerization reactionwhere the chemical product is a treatment fluid additive, and/orperforming the chemical process by adding a salt to water or a dilutebrine.

The exemplary method includes transferring the amount of heat to thefirst fluid such that the first fluid is heated at least 50° C. Themethod further includes providing a heat transfer environment such thatthe treatment fluid at a wellhead fluidly coupled to the wellbore is notmore than 10° C. warmer than a temperature of the first fluid before thetransferring the amount of heat.

Another exemplary embodiment is a method including providing a firstfluid, providing a first chemical reactant, performing a chemicalprocess including the first chemical reactant, and transferring anamount of heat from the chemical process to the first fluid. The methodfurther includes hydrating a polymer in the heated first fluid, andtreating a formation of interest with a treatment fluid including theheated first fluid and a chemical product of the chemical process. Themethod further includes diluting the treatment fluid with respect to atleast one constituent of the treatment fluid.

The exemplary method includes performing the chemical process by addingthe first chemical reactant to the first fluid, where the first chemicalreactant is a concentrated base, an anhydrous base, a concentrated acid,and/or an anhydrous acid. In certain embodiments, the method includesperforming the chemical process by adding the first chemical reactant tothe first fluid, providing a second chemical reactant and adding thesecond chemical reactant to the first fluid, where the first chemicalreactant is a concentrated base or an anhydrous base, and where thesecond chemical reactant is a concentrated acid or an anhydrous acid.The method further includes selecting an amount of the first fluid, anamount and concentration of the first chemical reactant, and an amountand concentration of the second chemical reactant to form a brine havinga specified salt concentration. The method may further includedynamically adjusting the specified salt concentration during thetreating.

In certain embodiments, the method includes selecting an amount of thefirst fluid, an amount and concentration of the first chemical reactant,and an amount and concentration of the second chemical reactant to forma brine having a temperature of at least 50° C. In certain embodiments,the method includes selecting an amount of the first fluid, an amountand concentration of the first chemical reactant, and an amount andconcentration of the second chemical reactant to form a brine having atemperature of at least 65° C. In certain embodiments, the methodincludes selecting an amount of the first fluid, an amount andconcentration of the first chemical reactant, and an amount andconcentration of the second chemical reactant to form a brine having aspecified temperature. The method may further include adjusting thespecified temperature during the treating.

In certain embodiments, the method includes adjusting a concentration ofthe polymer in the heated first fluid during the treating, and/ordynamically adjusting a concentration of the polymer in the treatmentfluid at a wellhead fluidly coupled to the formation of interest duringthe treating.

In certain embodiments, the method includes stopping the treating beforea pre-determined amount of the treatment fluid is injected into theformation of interest, where the pre-determined amount of the treatmentfluid is a design amount of the first chemical reactant. The methodfurther includes consuming less of the first chemical reactant than thedesign amount of the first chemical reactant. In an exemplaryembodiment, the method includes continuing the treating after apre-determined amount of the treatment fluid is injected into theformation of interest. In a further embodiment, the method includescontinuing the treating such that at least 60 m³ greater than thepre-determined amount of the treatment fluid is injected into theformation of interest.

Yet another exemplary embodiment is an apparatus including a treatmentconditions module that interprets a specified pumping rate and aspecified salt concentration, a hydration requirements module thatdetermines a hydration vessel fluid volume and/or a specifiedtemperature in response to the specified pumping rate, and a dynamicbrine generation module that controls a flow rate of a first fluid, abase material, an acid material, and a polymer material into a hydrationvessel in response to the specified salt concentration and the hydrationvessel fluid volume and/or the specified temperature. The apparatusfurther includes a treatment fluid flow module that controls a flow rateof a treatment fluid from the hydration vessel in response to thespecified pumping rate.

The treatment conditions module may further interpret the specifiedtemperature, and the hydration requirements module determines thehydration vessel fluid volume in response to the specified pumping rate.Alternately, the treatment conditions module may interpret the hydrationvessel fluid volume, and the hydration requirements module determinesthe specified temperature in response to the specified pumping rate. Incertain embodiments, the hydration requirements module determines ahydration time in response to the specified temperature and/or a presenttemperature of the treatment fluid in the hydration vessel.

The treatment conditions module may further interpret a dynamicallyupdated salt concentration, and the dynamic brine generation modulecontrols the flow rate of the first fluid, the base material, the acidmaterial, and the polymer material into the hydration vessel further inresponse to the dynamically updated salt concentration. The treatmentconditions module may further interpret a dynamically updated gelloading concentration, and the dynamic brine generation module controlsthe flow rate of the polymer material into the hydration vessel furtherin response to the dynamically updated gel loading concentration.

Yet another exemplary embodiment is a system including a fluid sourcethat provides a first fluid, a base source that provides a basematerial, and an acid source that provides an acid material, and apolymer source that provides a polymer material. The base materialincludes an anhydrous base and/or a concentrated base, and the acidmaterial includes an anhydrous acid and/or a concentrated acid. Thepolymer material includes a polymer such as xanthan,hydroxy-ethyl-cellulose, guar, carboxy-methyl-hydroxy-propyl-guar, apoly-saccharide, a poly-saccharide derivative, a poly-acrylamide, apoly-acrylamide co-polymer, diutan, hydroxyl-propyl guar, and/or asynthetic polymer.

The system further includes a hydration vessel fluidly coupled to thefluid source, the base source, the acid source, and the polymer source.The system further includes a fluid conduit fluidly coupled to the basesource, acid source, and polymer source on an upstream side and fluidlycoupled to a treatment pump on a downstream side, and a controllerstructured to: control a flow rate of a treatment fluid from thehydration vessel at a specified pumping rate, and to control a flow rateof the first fluid, the base material, the acid material, and thepolymer material into the hydration vessel such that the treatment fluidresiding in the hydration vessel comprises a specified saltconcentration and such that an average residence time of the treatmentfluid in the hydration vessel is at least equal to a hydration time.

The exemplary system further includes a bypass line fluidly coupling adiluted fluid to the treatment fluid downstream of the hydration vessel,where the diluted fluid may be the first fluid. In certain embodiments,the system further includes one or more heat exchangers thermallycoupled to the fluid conduit, where the controller controls the heatexchanger(s) such that a temperature of the treatment fluid exiting thefluid conduit is not more than 10° C. warmer than a temperature of thefirst fluid. An embodiment of the system includes the heat exchangertransferring thermal energy from the treatment fluid in the fluidconduit to the first fluid and/or an ambient fluid.

In certain embodiments, the controller further interprets a dynamicallyupdated salt concentration and controls the flow rate of the firstfluid, the base material, the acid material, and the polymer materialinto the hydration vessel such that the treatment fluid residing in thehydration vessel includes the dynamically updated salt concentration. Incertain embodiments, the controller further interprets a dynamicallyupdated gel loading and controls the flow rate of the first fluid, thebase material, the acid material, and the polymer material into thehydration vessel such that the treatment fluid residing in the hydrationvessel includes the dynamically updated gel loading.

In certain embodiments, the controller further interprets a dynamicallyupdated temperature and controls the flow rate of the first fluid, thebase material, the acid material, and the polymer material into thehydration vessel such that the treatment fluid residing in the hydrationvessel includes the dynamically updated temperature. In certainembodiments, the controller further interprets a temperature of thetreatment fluid in the hydration vessel and determines the hydrationtime in response to the temperature of the treatment fluid in thehydration vessel. In certain embodiments, the controller furtherinterprets a specified temperature and controls a flow rate of the firstfluid, the base material, the acid material, and the polymer materialinto the hydration vessel such that the treatment fluid residing in thehydration vessel includes the specified temperature. The specifiedtemperature may be a temperature at least 50° C. warmer than atemperature of the first fluid, a temperature of at least 65° C., and/ora temperature determined in response to an available volume of thehydration vessel and the specified pumping rate.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain exemplary embodiments have been shown and described andthat all changes and modifications that come within the spirit of theinventions are desired to be protected. In reading the claims, it isintended that when words such as “a,” “an,” “at least one,” or “at leastone portion” are used there is no intention to limit the claim to onlyone item unless specifically stated to the contrary in the claim. Whenthe language “at least a portion” and/or “a portion” is used the itemcan include a portion and/or the entire item unless specifically statedto the contrary.

1. An apparatus, comprising: a treatment conditions module structured tointerpret a specified pumping rate and a specified salt concentration; ahydration requirements module structured to determine at least one of ahydration vessel fluid volume and a specified temperature in response tothe specified pumping rate; a dynamic brine generation module structuredto control a flow rate of a first fluid; at least one of a claystabilizer precursor, an acid precursor and a base precursor; and apolymer material into a hydration vessel in response to the specifiedsalt concentration and the at least one of the hydration vessel fluidvolume and the specified temperature; and a treatment fluid flow modulestructured to control a flow rate of a treatment fluid from thehydration vessel in response to the specified pumping rate.
 2. Theapparatus of claim 1, wherein the treatment conditions module is furtherstructured to interpret the specified temperature, and wherein thehydration requirements module is structured to determine the hydrationvessel fluid volume in response to the specified pumping rate.
 3. Theapparatus of claim 1, wherein the treatment conditions module is furtherstructured to interpret the hydration vessel fluid volume, and whereinthe hydration requirements module is structured to determine thespecified temperature in response to the specified pumping rate.
 4. Theapparatus of claim 1, wherein the hydration requirements module isfurther structured to determine a hydration time in response to one ofthe specified temperature and a present temperature of the treatmentfluid in the hydration vessel.
 5. The apparatus of claim 1, wherein thetreatment conditions module is further structured to interpret adynamically updated salt concentration, and wherein the dynamic brinegeneration module is structured to control the flow rate of the firstfluid, at least one of the clay stabilizer precursor, the acid precursorand the base precursor, and the polymer material into the hydrationvessel further in response to the dynamically updated saltconcentration.
 6. The apparatus of claim 1, wherein the treatmentconditions module is further structured to interpret a dynamicallyupdated gel loading concentration, and wherein the dynamic brinegeneration module is structured to control the flow rate of the polymermaterial into the hydration vessel further in response to thedynamically updated gel loading concentration.
 7. A system, comprising:a fluid source structured to provide a first fluid; a salt sourcederived from at least one precursor material selected from the groupconsisting of a clay stabilizer precursor, an acid precursor and a baseprecursor; a polymer source structured to provide a polymer material; ahydration vessel fluidly coupled to the fluid source, the salt sourceand the polymer source; a fluid conduit fluidly coupled to the fluidsource, the salt source and the polymer source on an upstream side, andfluidly coupled to a treatment pump on a downstream side; a controllerstructured to: control a flow rate of a treatment fluid from thehydration vessel in response to a specified pumping rate; control a flowrate of the first fluid; at least one of the clay stabilizer precursor,the acid precursor and the base precursor; and the polymer material intothe hydration vessel such that the treatment fluid residing in thehydration vessel comprises a specified salt concentration and such thatan average residence time of the treatment fluid in the hydration vesselis at least equal to a hydration time.
 8. The system of claim 7, whereinthe polymer material comprises a polymer selected from the polymersconsisting of xanthan, hydroxy-ethyl-cellulose, guar,carboxy-methyl-hydroxy-propyl-guar, a poly-saccharide, a poly-saccharidederivative, a poly-acrylamide, a poly-acrylamide co-polymer, diutan,hydroxyl-propyl guar, and a synthetic polymer.
 9. The system of claim 7,further comprising a bypass line fluidly coupling a diluted fluid to thetreatment fluid downstream of the hydration vessel.
 10. The system ofclaim 9, wherein the diluted fluid comprises the first fluid.
 11. Thesystem of claim 7, further comprising at least one heat exchangerthermally coupled to the fluid conduit, wherein the controller isfurther structured to control the at least one heat exchanger such thata temperature of the treatment fluid exiting the fluid conduit is notmore than 10° C. warmer than a temperature of the first fluid.
 12. Thesystem of claim 11, wherein the at least one heat exchanger transfersthermal energy from the treatment fluid in the fluid conduit to at leastone fluid selected from the fluids consisting of the first fluid and anambient fluid.
 13. The system of claim 7, wherein the controller isfurther structured to interpret a dynamically updated salt concentrationand to further control the flow rate of the first fluid; at least one ofthe clay stabilizer precursor, the acid precursor and the baseprecursor; and the polymer material into the hydration vessel such thatthe treatment fluid residing in the hydration vessel comprises thedynamically updated salt concentration.
 14. The system of claim 7,wherein the controller is further structured to interpret a dynamicallyupdated gel loading and to further control the flow rate of the firstfluid; at least one of the clay stabilizer precursor, the acid precursorand the base precursor; and the polymer material into the hydrationvessel such that the treatment fluid residing in the hydration vesselcomprises the dynamically updated gel loading.
 15. The system of claim7, wherein the controller is further structured to interpret adynamically updated temperature and to further control the flow rate ofthe first fluid; at least one of the clay stabilizer precursor, the acidprecursor and the base precursor; and the polymer material into thehydration vessel such that the treatment fluid residing in the hydrationvessel comprises the dynamically updated temperature.
 16. The system ofclaim 7, wherein the controller is further structured to interpret atemperature of the treatment fluid in the hydration vessel and todetermine the hydration time in response to the temperature of thetreatment fluid in the hydration vessel.
 17. The system of claim 7,wherein the controller is further structured to interpret a specifiedtemperature and to control a flow rate of the first fluid; at least oneof the clay stabilizer precursor, the acid precursor and the baseprecursor; and the polymer material into the hydration vessel such thatthe treatment fluid residing in the hydration vessel comprises thespecified temperature.
 18. The system of claim 17, wherein the specifiedtemperature comprises a temperature selected from the temperaturesconsisting of: at least 50° C. warmer than a temperature of the firstfluid, at least 65° C., and a temperature determined in response to anavailable volume of the hydration vessel and the specified pumping rate.